Float actuated evaporator heater

ABSTRACT

The range of motion of the arm of a float which controls the energization of electrical heater elements disposed within a condensate receiving refrigerator pan will vaporize condensate therein from refrigerator cooling coils automatically to insure sufficient immersion of the heater elements to prevent overheating of the pan. The float actuates a magnetic reed switch which deenergizes the heater elements when the condensate surface level is reduced a small amount to open the contacts of the switch and thereby deenergize the heater.

United States Patent Canter FLOAT ACTUATED EVAPORATOR HEATER James A. Canter, Englewood, Ohio General Motors Corporation, Detroit, Mich.

June I, 1971 lnventor:

Assignee:

Filed:

Appl. No.:

U.S. Cl. ..2l9/272, 62/291, 219/275 Int. Cl 22b 1/28 Field of Search ..2l9/27l, 272, 275; 62/275,

62/289, 291, 150; ZOO/81.9 M; 335/205 References Cited UNITED STATES PATENTS 5/ l 967 Constantini et a1 ..2l9/27l [451 July 25, 1972 3,059,446 10/1962 Constantinietal ..62/150 2,892,051 6/1959 M0ore.....

Primary Examiner-C. L. Albritton Attorney-William S. Pettigrew, Frederick M. Ritchie a-id Edward P. Barthel [5 7] ABSTRACT The range of motion of the arm of a float which controls the energizationof electrical heater elements disposed within a condensate receiving refrigerator pan will vaporize condensate therein from refrigerator cooling coils automatically to insure sufficient immersion of the heater elements to prevent overheating of the pan. The float actuates a magnetic reed switch which deenergizes the heater elements when the condensate surface level is reduced a small amount to open the contacts of the switch and thereby deeuergize the heater.

3 Claims, 5 Drawing Figures MFEENTTED 111125 1912 ATTOP NEY FLOAT ACTUATED EVAPORATOR HEATER This invention relates to moisture vaporizing apparatus and more particularly to an apparatus for automatically disposing of condensate from the receiving pan of a domestic refrigerator.

ln frost free refrigerators it is necessary to periodically remove and dispose of frost accumulation on the heat exchanger or evaporator coils. To accomplish this it is common practice to raise the temperature of the heat exchanger above the freezing point of water and to dispose of the melted frost by means of including a drain or receiving pan having a suitable drain line for carrying water away from the unit. Since the drain pan is normally positioned in the machine compartment of the refrigerator the heat generated therein may be sufficient to vaporize the condensate. In cases where the temperature of the machine compartment is not sufficient to vaporize the condensate in the drain pan electrical heating means, such as an electrical heater element, may be located in the pan for vaporizing the condensate as it accumulates. It has been standard practice to incorporate a protective thermostat in the circuit of the heating means such that when the heater raises to a certain temperature it will actuate the thermostat and open circuit the electrical heater to prevent overheating of the drain pan together with the machine compartment of the floor surface beneath the refrigerator. It has been found that the temperature buildup of the heater may be such that, before the thermostat can be actuated, the temperature of the drain pan and the adjacent floor area will be subjected to a higher temperature than is desirable with resultant damage thereto.

It is therefore an object of the present invention to provide an improved float-type evaporator arrangement for vaporizing the water collected within the drain pan of a refrigerator which prevents overheating of the drain pan.

It is a further object of the invention to provide an improved float type evaporator unit for use with a condensate receiver which includes an improved electric heater energized by a float actuated magnetic switch which automatically deenergizes the heater when the condensate level in the receiver falls to a level such that the pan would be subjected to excessive heat.

Further objects and advantages of the present invention will be apparent from the following description, references being had to the accompanying drawing wherein a preferred form of the invention is clearly shown.

In the Drawings:

FIG. 1 is a side elevational view, partly in section, of a float actuated evaporator apparatus according to one form of the invention;

FIG. 2 is a top elevational view, partly in section, of the evaporator assembly;

FIG. 3 is a side elevational view of the evaporator of FIG. 2;

FIG. 4 is a perspective view of the evaporator device of FIG.

FIG. 5 is a schematic diagram of the heater circuit and switch.

As is shown in FIG. 1, a relatively large pan designated generally as is adapted to receive condensate liquid flowing from a suitable drain trap device of a domestic refrigerator. Drain pans of this type are usually formed of plastic material comprising a bottom wall 12 and vertical side walls 14 and end walls 16. A typical condensate drain tube and receiving pan arrangement is shown in US. Pat. No. 3,287,930 issued Nov. 29, 1966 by J. J. OConnell et al. The details of the drain tube and pan arrangement are unimportant to the present invention and while the preferred embodiment of the invention is disclosed in combination with a refrigerator persons skilled in the art will appreciate that it may be used in other related applicatrons.

The pan 10 has located therein a vaporizing heater assembly having four dimple-like legs 24 for supporting the heater assembly above the bottom surface of wall 12. The assembly 20 includes an immersion type heater 26 of known commercial type having a float 28 secured thereon by means of a pair of float arms 30 and 32 pivotally attached to the heater 26 by suitable means such as pins 34 and 36. The float 28 is formed of suitable material such as a plastic foam or the like and is generally rectangular in cross section and extends in a transverse direction substantially parallel to front wall 38 of the heater 26. The arms 30 and 32 are suitably affixed to the end surfaces 40 and 42 of the float such as by an epoxy cement.

A magnet indicated at 44 which in the preferred embodiment is circular or disc shaped in configuration is embedded in the float 30 substantially at the midpoint of its longitudinal axis so that it is symmetrically located in the vertical plane defined by the center line 45. It will be noted that a portion of the disc-shaped magnet extends outwardly or protrudes from the inner wall 46 of the float such that when the float rotates about the horizontal pivotal axis of pins 34, 36 upwardly on its float arms the exposed arcuate portion of the magnet will contact the front wall 38 of the heater 26 adjacent the upper edge thereof and is stopped thereby. By this arrangement the float arms 30, 32 attain a maximum angle of inclination from the horizontal of approximately 35 such that the magnet 44 will travel in an arcuate path of the order of 15 toward the upper edge of wall 38.

In the preferred form a standard dry or reed switch 50 of known commercial type is sealed or encapsulated in a glass tube 52 having two elongated electrically conductive reed members 54, 56 that are sealed, one at each end of tube 52, by mounting portions 58 and 60, respectively. The free contacting portions 62 and 64 of the reed members 54, 56 overlap at the center of the tube and are normally open or spaced by a short gap, as shown in FIG. 2, while dry nitrogen gas is forced into the tube 52 during the sealing operation creating an inert atmosphere for the contacts 62, 64. When the switch of this type is introduced into a magnetic field, the reeds 54, 56 become flux carriers, and the overlapping ends become opposite magnetic poles which attract each other. If the mag netic attraction between the reed contacts 62, 64 becomes strong enough to overcome the stiffness of the reeds, they move together and touch, completing the magnetic circuit and making electrical contact.

As seen in the schematic diagram of FIG. 5 the mounting portions 58, 60 of the reeds are electrically connected to resistance heaters 66, 68 respectively. The heater 66 may be connected by conductor 70 to a terminal T while the heater 68 connected through a thermostatic overheat-protective switch 72 and thence by conductor 74 to terminal T which terminals may be connected to a standard household 118 volt power source.

The evaporator unit according to the invention operates in the following manner. Typically, the conditions illustrated in FIG. 1 would represent the high water level 76 state of the condensate in the pan 10 so that as a consequence the float 28 and float arms 30, 32 move upward around the pivot pins 34, 36, consequently swinging the magnetic disc 44 upward in a clockwise direction, thereby contacting the wall 38 of the immersion heater. As a result the reed contacts 62, 64 are closed and the heater elements 66, 68 are energized causing a vaporization of the water within the pan with the attendant fall in level of the condensate and float 28 resulting in opening of the contacts 62, 64 of the reed switch. This action swings the float 28 in a counterclockwise direction moving the magnet 44 outwardly and downwardly from the contacts 62, 64 and immediately opening the circuit and deenergizing the elements 66 and 68 again permitting the water level to rise to a point where the float 28 will again rise and close the contacts 62, 64. Because of the small swinging movement required to energize and deenergize the reed switch the level 76 of the condensate is maintained at an elevation to provide substantial cooling of the heater 26 by the water to prevent overheating of the pan l0 and possible damage to the refrigerator components or adjacent floor area.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is:

1. A float actuated heater apparatus for regulating the level of defrost water in a condensation collecting receiver pan of a domestic refrigerator comprising an immersion electric heater body having resistance heaters embedded therein including an electrical heating circuit for energizing said resistance heaters, a pair of spaced flat support arms pivotally mounted on said heater body about a horizontal axis, a float on said float arms responsive to a rise or fall of water level in the collecting pan, said heat body including a normally open reed switch located thereon operative to open and close the circuit of said resistance heaters, said reed switch having a pair of reeds sealed in a glass tube each having a mounting portion and a contacting portion spaced longitudinally on the reed, said reeds having their contacting portions in overlying relationship with one another, the longitudinal axis of said reed switch located parallel to the horizontal pivotal axis of said float arms, a magnet incorporated with said float so as to be movable in an arcuate path in accordance with the float elevation toward and away from said reed switch, the path of said magnet defining a vertical plane substantially bisecting said reed switch contacting portions whereby said reed switch is sensitive to a relatively small rise of the water level in the pan to cause said magnet to close said reed switch contacts and energize said heater elements, and whereby a relatively small decrease in the water level pivots said magnet away from said reed switch contacts allowing them to open thereby deenergizing said resistance heaters and maintaining in said pan a minimum volume of water at a level sufficient to maintain said heating assembly partially submerged in the water.

2, A float actuated heater apparatus for regulating the level of defrost water in a condensation collecting receiver pan of a domestic refrigerator comprising a rectangular shape in plan immersion electric heater body having resistance heaters embedded therein including an electrical heating circuit for energizing said resistance heaters, a pair of spaced float arms pivotally mounted on a horizontal axis at points on said heater body side walls adjacent the forward lower edge of said heater body, a float on said float arms and extending therebetween substantially coextensive with the front wall of said heater body, said heater body including a normally open reed switch embedded therein at a point adjacent the front wall upper edge of said heater body operative to open and close the circuit of said resistance heaters, said reed switch having its longitudinal axis parallel to said float arm pivotal axis and including a pair of reeds sealed in a glass tube each reed having a mounting portionand a contacting portion spaced longitudinally thereon, said reeds having their contacting portions in overlying relationship with one another, the longitudinal axis of said reed switch located parallel to the horizontal pivotal axis of said float arms, a magnet incorporated with said float so as to be movable in an arcuate path in accordance with the float movement toward and away from said reed switch, said float operative to swing in an upward direction from a substantially horizontal plane to contact said heater body adjacent said front wall upper edge to limit the uppermost extent of its pivotal rising motion when said magnet is disposed adjacent the upper edge of said heater body, the path of said magnet defining a vertical plane substantially bisecting said reed switch contacting portions whereby said reed switch is sensitive to a relatively small rise of the water level in the pan to cause said magnet to close said reed switch contacts and energize said heater element, and whereby a relatively small decrease in the water level pivots said magnet away from said reed switch contacts allowing them to open thereby deenergiz ing said resistance elements and maintaining in said pan a minimum volume of water at a level sufficient to maintain said heater body partially submerged in the water. I

3. The float actuated heater apparatus as defined in claim 2 wherein said float is rectangular in cross section and said magnet is in the form of a disc embedded in said float such that an arcuate section of said disc extends outwardly from a side wall of said float towards said heater body front wall, said arcuate section operative to contact said heater body front wall to limit the uppermost extent of the pivotal rising motion of said mg UNITED STATES PATIENT OFFHIE TEFICATE 0F CGRREQTWN Patent No. 3,679,867 Dated July 25 1972 lnventor (is) James A. Canter It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

column 3, line 6, (Claim 1) "flat" should read float o Signed and sealed this 10th day of April 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR.

ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 3 UNITED STATES PATENT oTTTeT CETEFECAE 5* CQEQHQN Patent No. 3,679,867 Dated July 25 1972 Inventorfls) James A. Canter It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 6, (Claim 1) "flat" should rea Signed and sealed this 10th day of April 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attestlng Officer Commissioner of Patents 

1. A float actuated heater apparatus for regulating the level of defrost water in a condensation collecting receiver pan of a domestic refrigerator comprising an immersion electric heater body having resistance heaters embedded therein including an electrical heating circuit for energizing said resistance heaters, a pair of spaced flat support arms pivotally mounted on said heater body about a horizontal axis, a float on said float arms responsive to a rise or fall of water level in the collecting pan, said heat body including a normally open reed switch located thereon operative to open and close the circuit of said resistance heaters, said reed switch having a pair of reeds sealed in a glass tube each having a mounting portion and a contacting portion spaced longitudinally on the reed, said reeds having their contacting portions in overlying relationship with one another, the longitudinal axis of said reed switch located parallel to the horizontal pivotal axis of said float arms, a magnet incorporated with said float so as to be movable in an arcuate path in accordance with the float elevation toward and away from said reed switch, the path of said magnet defining a vertical plane substantially bisecting said reed switch contacting portions whereby said reed switch is sensitive to a relatively small rise of the water level in the pan to cause said magnet to close said reed switch contacts and energize said heater elements, and whereby a relatively small decrease in the water level pivots said magnet away from said reed switch contacts allowing them to open thereby deenergizing said resistance heaters and maintaining in said pan a minimum volume of water at a level sufficient to maintain said heating assembly partially submerged in the water.
 2. A float actuated heater apparatus for regulating the level of defrost water in a condensation collecting receiver pan of a domestic refrigerator comprising a rectangular shape in plan immersion electric heater body having resistance heaters embedded therein including an electrical heating circuit for energizing said resistance heaters, a pair of spaced float arms pivotally mounted on a horizontal axis at points on said heater body side walls adjacent the forward lower edge of said heater body, a float on said float arms and extending therebetween substantially coextensive with the front wall of said heater body, said heater body including a normally open reed switch embedded therein at a point adjacent the front wall upper edge of said heater bOdy operative to open and close the circuit of said resistance heaters, said reed switch having its longitudinal axis parallel to said float arm pivotal axis and including a pair of reeds sealed in a glass tube each reed having a mounting portion and a contacting portion spaced longitudinally thereon, said reeds having their contacting portions in overlying relationship with one another, the longitudinal axis of said reed switch located parallel to the horizontal pivotal axis of said float arms, a magnet incorporated with said float so as to be movable in an arcuate path in accordance with the float movement toward and away from said reed switch, said float operative to swing in an upward direction from a substantially horizontal plane to contact said heater body adjacent said front wall upper edge to limit the uppermost extent of its pivotal rising motion when said magnet is disposed adjacent the upper edge of said heater body, the path of said magnet defining a vertical plane substantially bisecting said reed switch contacting portions whereby said reed switch is sensitive to a relatively small rise of the water level in the pan to cause said magnet to close said reed switch contacts and energize said heater element, and whereby a relatively small decrease in the water level pivots said magnet away from said reed switch contacts allowing them to open thereby deenergizing said resistance elements and maintaining in said pan a minimum volume of water at a level sufficient to maintain said heater body partially submerged in the water.
 3. The float actuated heater apparatus as defined in claim 2 wherein said float is rectangular in cross section and said magnet is in the form of a disc embedded in said float such that an arcuate section of said disc extends outwardly from a side wall of said float towards said heater body front wall, said arcuate section operative to contact said heater body front wall to limit the uppermost extent of the pivotal rising motion of said float. 